On Mon, 30 Mar 2020, 15:22 Valentin Schweitzer, <[email protected]> wrote:
> 1234567890123456789012345678901234567890123456789012345678901234567890 > > Hi, > > when using scale_npp to scale a test video down from 1920x1080 to > 1024x576 or lower with multiple processes in parallel, CPU usage is > unusually high.For context, when scaling the same video down to > 1280x720, CPU usage stays at about0.5% per FFmpeg instance. When > scaling down too 1024x576 or lower, CPU usage per FFmpeg process rises > to about 3.0%. The values listed here appear when starting 29 > instances of FFmpeg in parallel. The effect is less pronounced but > still visible at 10 instances in parallel. Hardware used for this > is an AMD EPYC 7401P 24 Core + NVIDIA Quadro RTX 4000. > > To generate 100s of random noise in 1080p (which will be the test video): > > ffmpeg -y -hide_banner -f lavfi -i nullsrc=s=1920x1080 -filter_complex > "geq=random(1)*255:128:128;aevalsrc=-2+random(0)" -vcodec rawvideo > -acodec pcm_s16le -t 100 noise.mkv > > Now rescale the test video to 720p: > > ffmpeg -hide_banner -y -i noise.mkv -vf > hwupload_cuda,scale_npp=w=1280:h=720:format=nv12 -vcodec h264_nvenc -an > -f null NUL > > This should not cause very high CPU usage. Now rescale the same video to > 576p: > > ffmpeg -hide_banner -y -i noise.mkv -vf > hwupload_cuda,scale_npp=w=1024:h=576:format=nv12 -vcodec h264_nvenc -an > -f null NUL > > This should cause about 5 or 6 times as much CPU usage. > > This might be caused by some NVIDIA optimizations, but it does not > seem to be documented and I have yet to find a good place to ask > Set this environment variable: CUDA_DEVICE_MAX_CONNECTIONS=2 Then retest and report back. > _______________________________________________ ffmpeg-user mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
